Vehicles such as tractor trailers and the like transport materials over great distances via highway systems. These materials include gravel, dirt, and other loose materials in which an uncovered or open-bed trailer is utilized for the transport of such materials.
The trailers typically comprise a bottom and four sidewalls with an open top. The open top allows equipment such as a front-end loader to load the materials by emptying the contents of the loader over one of the sidewalls. After the load is transferred into the open-bed trailer, the load may be covered by a tarpaulin. The use of a tarpaulin protects the materials in the trailer from the elements such as wind and precipitation. The tarp also has the added benefit of protecting other motorists from debris leaving the trailer. The prior art utilized rods spanning the width or length of the open top to assist in the support of the tarpaulin.
Improvements were then made to the support rods by giving them an arch shape wherein the central region of the support rod was at a higher elevation than the two ends of the support rod. Hence, the support rods became known as tarpaulin bows or tarp bows. This particular improvement to the support rods allowed a greater load capacity. Furthermore, the arch shape of the support rods allowed water to run off the tarp and over the sides of the flatbed trailer.
Typically, tarp bows are selectively attached to the sidewalls of the trailer by means of a coupling mechanism. The personnel loading an open-bed trailer had two options, one, remove the tarp bows prior to loading, or two, load the trailer while the tarp bows stretch the width of the open-bed trailer. Either option leads to its own disadvantages. Removing the tarp bows increases the expense of manpower and also expends manpower costs in reattaching the tarp bows once the load has been placed in the trailer. The second option leads to damage of the tarp bows due to contact by the frontend loader. As the frontend loader's bucket is positioned over the sidewalls, it is not uncommon for the bucket to make contact with the tarp bows. Depending on the forces exerted on the tarp bows by a frontend loader or other piece of equipment, the bows may be damaged or completely broken. The damaged tarp bows must then be replaced, adding business costs to companies involved in transporting materials.
Improvements were then designed to reduce the time for removal and reattachment of the tarp bows or designed to increase the flexibility of the tarp bows. As an example, Stephens (U.S. Reissue 36,748) utilizes a flexible tarp bow which flexes when the bucket of a frontend loader or similar piece of equipment makes contact with the tarp bow. Similarly, Barkus (U.S. Pat. No. 5,211,441) implements a hinged tarp bow such that the bow can move downward a certain distance. Both inventions sought to reduce the number of tarp bows damaged in the loading process.